Undiagnosed pulmonary tuberculosis among prisoners in Malaysia: an overlooked risk for tuberculosis in the community

Objectives: To investigate the prevalence of previously undiagnosed active tuberculosis (TB) cases among prisoners in Malaysia's largest prison using an intensified TB case-finding strategy. Methods: From October 2012 to May 2013, prisoners housed in two distinct units (HIV-negative and HIV-positive) were approached to participate in the TB screening study. Consenting prisoners submitted two sputum samples that were examined using GeneXpert MTB/RIF, smear microscopy and liquid culture. Socio-demographic and clinical information was collected and correlates of active TB, defined as having either a positive GeneXpert MTB/RIF or culture results, were assessed using regression analyses. Results: Among the total of 559 prisoners, 442 (79.1%) had complete data; 28.7% were HIV-infected, 80.8% were men and the average age was 36.4 (SD 9.8) years. Overall, 34 (7.7%) had previously undiagnosed active TB, of whom 64.7% were unable to complete their TB treatment in prison due to insufficient time (<6 months) remaining in prison. Previously undiagnosed active TB was independently associated with older age groups (AOR 11.44 and 6.06 for age ≥ 50 and age 40–49 years, respectively) and with higher levels of immunosuppression (CD4 < 200 cells/ml) in HIV-infected prisoners (AOR 3.07, 95% CI 1.03–9.17). Conclusions: The high prevalence of previously undiagnosed active TB in this prison highlights the inadequate performance of internationally recommended case-finding strategies and suggests that passive case-finding policies should be abandoned, especially in prison settings where HIV infection is prevalent. Moreover, partnerships between criminal justice and public health treatment systems are crucial to continue TB treatment after release.